stop-timer

Arguments:
timer

Stops timer, which must be an instance of the timer class, from running (if it is
running). That is, it makes its active property nil.

If a timer is intended to fire only once after it is started, then stop-timer can be called in the timer's on-timer function to prevent further firings until the timer is restarted. Otherwise stop-timer may be called at any arbitrary time when no further firings are desired.